Abstract

Recent studies in monkeys suggest that neurons in sensorimotor circuits involved in perceptual decision-making also play a role in decision confidence. Based on these studies, confidence is considered to be an optimal readout of the probability that a decision is correct, as confidence is often correlated with decision accuracy. Here, we record neuronal activity from a sensorimotor decision area, the superior colliculus (SC), during two different tasks to investigate whether population-level activity in this area signals different types of perceptual confidence. In one task, decision accuracy and confidence co-vary, allowing us to determine if neural activity in the SC reflects 'optimal confidence,' as previously demonstrated in cortical areas. In our second task, we implement a novel motion discrimination task with stimuli that are matched for decision accuracy (and thus 'optimal confidence') but produce different behavioral reports about confidence (i.e., 'subjective confidence'). In our first task, we predicted choices from neuronal population activity using a multivariate decoder and found that decoding performance increased as decision accuracy increased, indicating a role for the SC in optimal confidence. In our second task, across two conditions in which decision accuracy was matched, performance of the decoder was similar between high and low confidence conditions, indicating the SC is unlikely to be involved in subjective confidence. These results show that the SC signals optimal decision confidence similar to area LIP of cortex and also motivate future investigations to determine where in the brain signals related to subjective confidence reside.